Dave, Let's use this page to create a Microscope-Generated timeline. Each bullet point would represent a PERIOD card, with sub-points to represent how they may be modified by an EVENT or SCENE.

BIG PICTURE: Over fifty years, Gotham's original flaws of neglect and greed tear the fabric of the city apart to expose its dark, rotten core

PALETTE: This is a list of things we want in our campaign, and things we don't want. Let's just throw these in a list here for the time being.

We'll take turns adding a PERIOD, an EVENT, or a SCENE.

• HISTORY START : The main gangs of Gotham have taken root and just begin to choke Gotham's prosperity and optimism (DARK)
• Industrial Period : During this period famous industrialists built infrastructure including roads, sanitation, and most notably bridges in Gotham to try to improve the city's prosperity (LIGHT)
• Immigration Period : This period of increased immigration from overseas - particularly Italy and China - helped to fuel the city's growth, but also brought on more strife (DARK)
• Period of the Victorian Legion : During this period, a group of gentlemen adventurers teamed up to help free Gotham of crime, only to be ultimately defeated and destroyed from within (LIGHT)
• The Great Gotham Fire of 1911 This period followed a blaze that destroyed a large section of the city and led to a period of civil disorder and unrest until the damage was repaired (DARK)
• The Roaring 20's : This was a period of sustained economic prosperity with a distinctive cultural edge (LIGHT)
• The Great Depression : Following the stock market crash of 1929, this period of Gotham's history marks the severe downturn in the economic status of the city (DARK)
• CAMPAIGN START : The beginning of the campaign in Depression-Era Gotham with all gangs represented (DARK)

https://en.wikipedia.org/wiki/Gotham_City#Fictional_history